1. Field of the Invention
The present invention relates to an optical ferrule. Specifically, the present invention relates to an optical ferrule that is butt-connected in an optical adapter by being guided by guide pins.
2. Description of the Related Art
In general, an optical ferrule (optical connector), which is standardized according to JIS C 5981, IEC 61754-5 and the like, is called an MT (Mechanically Transferable) ferrule (MT connector). The MT ferrule is used for connecting one or more optical, and has a positioning mechanism by use of guide pins for a high-accuracy positioning of each optical fiber.
The MT ferrule is provided with a pair of guide pin insertion holes on an end surface thereof to insert the guide pins for positioning the optical ferrule, and also provided with optical fiber insertion holes to insert the respective optical fibers between the guide pins. The optical fiber insertion holes are aligned in the same direction as a direction in which the two guide pin insertion holes are arrayed. The respective optical fibers are inserted into the optical fiber insertion holes from a rear end of the MT ferrule, and fixed by filling with an adhesive agent from an opening potion on an upper surface of the MT ferrule.
According to the above-mentioned Japanese Industrial Standards, a spring clamp is employed for the connection of the MT ferrule. Meanwhile, an optical adapter that is easy to handle the connection can be used. The optical adapter, which is formed in a shape of a rectangular cylinder, is provided with openings for inserting the MT ferrule, and a latch mechanism inside the openings. The latch mechanism is configured as a flexible arm provided with a claw at a front edge portion thereof. A base portion of the arm is fixed to an inner wall of the optical adapter. When the MT ferrule is inserted into the optical adapter, the claw locks a flange formed at a rear portion of the MT ferrule so that the MT ferrule is securely fixed in the optical adapter.
The MT ferrule is optically connected by means of a so-called PC (Physical Contact) connection. In such a case, optical transmission performance is strongly dependent on connecting conditions such as axis misalignment and inclination of optical fibers, and gaps between each optical fiber. Therefore, it is necessary to remove foreign materials adhered to a connection end face of the MT ferrule during connecting so as to avoid the increase of connection loss. The foreign materials are commonly wiped off by use of a cleaner. However, connection loss at the PC connection may increase during wiping off, because some of the foreign materials may be gathered and deposited around base portions of the guide pins.
Japanese Patent Application Laid-Open Publication No. 2004-093992 (Patent Document 1) discloses a MT ferrule capable of lowering connection loss caused by deposition of foreign materials. According to Patent Document 1, the MT ferrule is provided with a pair of grooves with a certain depth on a connection end face, in which the grooves are provided perpendicular to an alignment of optical fiber insertion holes. While, guide pin insertion holes are formed in bottom surfaces of the respective grooves. Thus, it is possible to prevent the foreign materials from interfering a PC connection since the rest of the foreign materials after cleaning are gathered in the grooves.